The present invention relates generally to chucks for use with drills or other tool drivers.
Tool drivers of various types are well known, including hand-actuated drivers as well as electric or pneumatic drivers. Although twist drills are a common tool utilized with such drivers, the tools may also comprise screwdrivers, nut drivers, burrs, mounted grinding stones and other cutting or abrading tools. Since the tools may have shanks of varying diameter or the cross-section of the tool shank may be polygonal, the device is usually provided with a chuck which is adjustable over a relatively wide range. The chuck may be attached to the output shaft of the driver by a threaded or tapered bore.
A variety of chucks have been developed in the art. In one form of chuck, three jaws are circumferentially spaced by approximately 120 degrees from each other. Such jaws are constrained by angularly disposed passageways in a body attached to the driver's output shaft. These passageways are configured so that rotation of the body in one direction relative to a constrained nut engaging the jaws will cause the jaws to grip the cylindrical shank of a tool. Rotation of the body in the opposite direction with respect to the constrained nut releases the gripping relationship of the jaws.
Such a chuck may be keyless if the relative rotation between the body and the nut is effected by hand. One example of such a chuck is disclosed in U.S. Pat. No. 5,348,317, entitled "Chuck." This patent, which is commonly assigned to the present assignee, is incorporated fully herein by reference.
The respective jaws of these chucks include a generally oblique surface defining thereon a "bite" for engaging the tool shank. In the past, the bite has been formed by milling or grinding a "blank" piece of metal having a length substantially equal to the finished length of the jaw. While this technique generally produced suitable jaws, it has not been without disadvantages. For example, because the bite is formed by removal of metal, the blank begins with a volume of metal significantly greater than that of the finished jaw member. In a mass production situation, the cost attributed to the removed metal can be appreciable. Furthermore, the milling or grinding operation utilized to form the bite must be one of relative precision to ensure that the jaw members properly converge to grip the shank of a tool. Accordingly, milling or grinding may introduce problems into the manufacture of chucks.